Application of auxiliary lighting in automatic hitch operation

ABSTRACT

A vehicle hitching assistance system includes a controller acquiring image data from the vehicle and identifying a trailer within a specified area of the image data and then identifying a coupler of the trailer. The specified area is less than a total field of the image data. The controller then outputs a steering signal to the vehicle to cause the vehicle to steer to align a hitch ball of the vehicle with the coupler.

FIELD OF THE INVENTION

The present invention generally relates to a vehicle hitch assistancesystem. In particular, the system provides the user with various optionsfor assisting in hitching a vehicle with a trailer and targets forinitial alignment of the vehicle prior to assistance in hitching.

BACKGROUND OF THE INVENTION

Hitching a trailer to a vehicle can be a difficult and time-consumingexperience. In particular, aligning a vehicle hitch ball with thedesired trailer hitch can, depending on the initial location of thetrailer relative to the vehicle, require repeated forward and reversedriving coordinated with multiple steering maneuvers to appropriatelyposition the vehicle. Further, through a significant portion of thedriving needed for appropriate hitch ball alignment, the trailer hitchcannot be seen, and the hitch ball can, under ordinary circumstance,never actually be seen by the driver. This lack of sight lines requiresinference of the positioning of the hitch ball and hitch based onexperience with a particular vehicle and trailer, and can still requiremultiple instances of stopping and stepping out of the vehicle toconfirm alignment or to note an appropriate correction for a subsequentset of maneuvers. Even further, the closeness of the hitch ball to therear bumper of the vehicle means that any overshoot can cause acollision of the vehicle with the trailer. Accordingly, furtheradvancements may be desired.

SUMMARY OF THE INVENTION

According to one aspect of the disclosure, a vehicle hitching assistancesystem includes a controller acquiring image data from the vehicle andidentifying a trailer within a specified area of the image data and thenidentifying a coupler of the trailer. The specified area is less than atotal field of the image data. The controller then outputs a steeringsignal to the vehicle to cause the vehicle to steer to align a hitchball of the vehicle with the coupler.

Embodiments of the first aspect of the disclosure can include any one ora combination of the following features or aspects:

the controller may acquire the image data from an imaging systemincluded with the vehicle, the imaging system having at least onecamera, the total field of the image data corresponding with a totalfield of view of the at least one camera;

the controller may output the steering signal to a steering systemincluded with the vehicle, and the controller may derive the steeringsignal based on at least a maximum steering angle of the steeringsystem;

the specified area of the image data can be a target area disposedwithin a central portion of the image data;

the specified area of the image data can be within a designated boundarycomprising respective portions based on a resolution of the image data,a proportion of the trailer relative to the total field, and a knownsteering limit of the vehicle;

the respective portions of the designated boundary may be based on acorrelation of the total field of the image data with an area of anassumed ground plane on which the vehicle is positioned visible withinthe total field;

the area of the assumed ground plane may include a maximum couplerdetection distance corresponding with the resolution of the image data,a minimum trailer identification distance corresponding with theproportion of the trailer relative to the total field, and left andright maximum steerable paths extending from the vehicle in a reversingdirection corresponding with the known steering limit of the vehicle;

the controller may further output a video image displayable on ahuman-machine interface within the vehicle including the image data anda graphic overlay of the specified area on the image data in aproportionally correlated manner;

the controller may output the graphic overlay in the video image uponactivation of the system;

the controller may receive an input from the human-machine interfacecorresponding with a user indication of a trailer within the image dataand may output the graphic overlay in the video image only afterreceiving the user indication of the trailer within the image data andfailing to identify a trailer within the specified area of the imagedata;

the controller may further cause the vehicle to illuminate one or moreexterior lights directed toward a rear of the vehicle prior to acquiringthe image data from the vehicle; and

the controller may identify the trailer within the specified area of theimage data and then identify a coupler of the trailer and output asteering signal to the vehicle to cause the vehicle to steer to an aligna hitch ball of the vehicle with the coupler as a part of a first hitchassist mode implemented when the controller determines that a sensingcondition and a visibility condition are met, further implement a secondhitch assistance mode when one of the sensing condition and thevisibility condition are not met, receive a selection signal from thevehicle corresponding with a user selection of a mode beforeimplementing either the first or second hitch assistance mode, and causethe vehicle to present an indication that the first hitch assist modemay not be selected when one of the sensing condition and the visibilitycondition are not met.

According to another aspect of the disclosure, a vehicle includes asteering system, at least one exterior light mounted on and directedaway from a rear of the vehicle, and a controller. The controller causesthe at least one exterior light to illuminate, acquiring image data fromthe vehicle, identifies a trailer within the image data, and outputs asteering signal to the vehicle steering system to an align a hitch ballof the vehicle with a coupler of the trailer.

According to another aspect of the disclosure, a method for assisting avehicle in hitching with a trailer includes acquiring image data for afield of view away from a rear of the vehicle, identifying a trailerwithin a specified area less than the field of view of the image dataand then identifying a coupler of the trailer, and outputting a steeringsignal to cause the vehicle to steer to an align a hitch ball of thevehicle with the coupler.

These and other aspects, objects, and features of the present inventionwill be understood and appreciated by those skilled in the art uponstudying the following specification, claims, and appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a perspective view of a vehicle in an unhitched positionrelative to a trailer;

FIG. 2 is a diagram of a system according to an aspect of the disclosurefor assisting in aligning the vehicle with a trailer in a position forhitching the trailer to the vehicle;

FIG. 3 is a depiction of an image received from a vehicle camera duringan alignment sequence step with a target overlaid thereon;

FIG. 4 is an further depiction of an image received from a vehiclecamera during a subsequent alignment sequence step with the target andadditional information overlaid thereon;

FIG. 5 is an overhead schematic view of a vehicle during a step of thealignment sequence with the trailer;

FIG. 6 is a depiction of an image received from the vehicle cameraduring an alternative alignment sequence step with a various guidancepaths overlaid thereon;

FIG. 7 is a flowchart depicting a sequence in presenting variousalignment modes for selection by a user;

FIG. 8 is a depiction of a menu presentable to a user via a vehiclehuman-machine interface for selection of an alignment mode according toFIG. 7;

FIG. 9 is a schematic depiction of a valid zone for traileridentification based on alignment with a vehicle including a systemaccording to FIG. 2;

FIG. 10 is a depiction of an image received from a vehicle camera duringan alternative alignment sequence step with an alternative targetoverlaid thereon;

FIG. 11 is an further depiction of a subsequent image received from avehicle camera during a subsequent alignment sequence step with thetarget and additional information overlaid thereon;

FIG. 12 is a depiction of an image received from a vehicle camera duringan alternative alignment sequence step with an alternative targetoverlaid thereon;

FIG. 13 is a schematic depiction of an alternative valid zone fortrailer identification based on alignment with a vehicle including asystem according to FIG. 2;

FIG. 14 is a flowchart depicting a sequence in guiding a vehicle intoalignment with a trailer for identification thereof by a systemaccording to FIG. 2;

FIG. 15 is a depiction of an image received from a vehicle camera duringthe alignment sequence step of the sequence of FIG. 14 with analternative target overlaid thereon;

FIG. 16 is a flowchart depicting an alternative sequence in guiding avehicle into alignment with a trailer for identification thereof by asystem according to FIG. 2;

FIGS. 17A and 17B are depictions of respective image received from avehicle camera during alignment sequence steps of the sequence of FIG.16;

FIG. 18 is an overhead schematic view of portions to the rear of avehicle illuminated by various exterior lights included on the vehicle;

FIG. 19 is a flowchart depicting a sequence of selectively usingexterior vehicle lights to improve the ability of a system according toFIG. 2 to detect a trailer;

FIG. 20 is an overhead schematic view of the vehicle during a subsequentstep of the alignment sequence with the trailer;

FIG. 21 is a depiction of an image received from a vehicle camera duringthe alignment sequence step of FIG. 7;

FIG. 22 is an overhead schematic view of the vehicle during a subsequentstep of the alignment sequence with the trailer;

FIG. 23 is an overhead schematic view of the vehicle during a subsequentstep of the alignment sequence with the trailer and showing the positionof a hitch ball of the vehicle at an end of a derived alignment path;and

FIG. 24 is a flowchart depicting steps in the alignment sequence.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

For purposes of description herein, the terms “upper,” “lower,” “right,”“left,” “rear,” “front,” “vertical,” “horizontal,” “interior,”“exterior,” and derivatives thereof shall relate to the device asoriented in FIG. 1. However, it is to be understood that the device mayassume various alternative orientations, except where expresslyspecified to the contrary. It is also to be understood that the specificdevices and processes illustrated in the attached drawing, and describedin the following specification are simply exemplary embodiments of theinventive concepts defined in the appended claims. Hence, specificdimensions and other physical characteristics relating to theembodiments disclosed herein are not to be considered as limiting,unless the claims expressly state otherwise. Additionally, unlessotherwise specified, it is to be understood that discussion of aparticular feature of component extending in or along a given directionor the like does not mean that the feature or component follows astraight line or axis in such a direction or that it only extends insuch direction or on such a plane without other directional componentsor deviations, unless otherwise specified.

Referring generally to FIGS. 1 and 2, reference numeral 10 designates ahitch assistance system (also referred to as a “hitch assist” system)for a vehicle 12. In particular, hitch assistance system 10 includes acontroller 26 a controller acquiring image data 55 from the vehicle 12and identifying a trailer 16 within a specified area 45 of the imagedata 55 and then identifying a coupler 14 of the trailer 16, thespecified area 45 being less than a total field 53 of the image data 55.The controller 26 further outputs a steering signal to the vehicle 12 tocause the vehicle 12 to steer to align a hitch ball 34 of the vehicle 12with the coupler 34.

With respect to the general operation of the hitch assist system 10, asillustrated in the system diagram of FIG. 2, system 10 includes varioussensors and devices that obtain or otherwise provide vehiclestatus-related information. This information includes positioninginformation from a positioning system 22, which may include a deadreckoning device 24 or, in addition or as an alternative, a globalpositioning system (GPS), to determine a coordinate location of thevehicle 12 based on the one or more locations of the devices within thepositioning system 22. In particular, the dead reckoning device 24 canestablish and track the coordinate location of the vehicle 12 within alocalized coordinate system 82 based at least on vehicle speed andsteering angle δ. Other vehicle information received by hitch assistsystem 10 may include a speed of the vehicle 12 from a speed sensor 56and a yaw rate of the vehicle 12 from a yaw rate sensor 58. It iscontemplated that in additional embodiments, a proximity sensor 54 or anarray thereof, and other vehicle sensors and devices may provide sensorsignals or other information, such as sequential images of a trailer 16,including the detected coupler 14, that the controller 26 of the hitchassist system 10 may process with various routines to determine theheight H and position (e.g., based on the distance D_(h) and angleα_(h)) of coupler 14.

As further shown in FIG. 2, one embodiment of the hitch assist system 10is in communication with the steering system 20 of vehicle 12, which maybe a power assist steering system 20 including an electric steeringmotor 74 to operate the steered wheels 76 (FIG. 1) of the vehicle 12 formoving the vehicle 12 in such a manner that the vehicle yaw changes withthe vehicle velocity and the steering angle δ. In the illustratedembodiment, the power assist steering system 20 is an electricpower-assisted steering (“EPAS”) system including electric steeringmotor 74 for turning the steered wheels 76 to a steering angle δ basedon a steering command, whereby the steering angle δ may be sensed by asteering angle sensor 78 of the power assist steering system 20. Thesteering command 69 may be provided by the hitch assist system 10 forautonomously steering during a trailer hitch alignment maneuver and mayalternatively be provided manually via a rotational position (e.g.,steering wheel angle) of a steering wheel of vehicle 12. However, in theillustrated embodiment, the steering wheel of the vehicle 12 ismechanically coupled with the steered wheels 76 of the vehicle 12, suchthat the steering wheel moves in concert with steered wheels 76,preventing manual intervention with the steering wheel during autonomoussteering. More specifically, a torque sensor 80 is provided on the powerassist steering system 20 that senses torque on the steering wheel thatis not expected from autonomous control of the steering wheel andtherefore indicative of manual intervention, whereby the hitch assistsystem 10 may alert the driver to discontinue manual intervention withthe steering wheel and/or discontinue autonomous steering. Inalternative embodiments, some vehicles have a power assist steeringsystem 20 that allows a steering wheel to be partially decoupled frommovement of the steered wheels 76 of such a vehicle.

With continued reference to FIG. 2, the power assist steering system 20provides the controller 26 of the hitch assist system 10 withinformation relating to a rotational position of steered wheels 76 ofthe vehicle 12, including a steering angle δ. The controller 26 in theillustrated embodiment processes the current steering angle, in additionto other vehicle 12 conditions to guide the vehicle 12 along the desiredpath 32 (FIG. 3). It is conceivable that the hitch assist system 10, inadditional embodiments, may be an integrated component of the powerassist steering system 20. For example, the power assist steering system20 may include a hitch assist algorithm for generating vehicle steeringinformation and commands as a function of all or a portion ofinformation received from the imaging system 18, the power assiststeering system 20, a vehicle brake control system 70, a powertraincontrol system 72, and other vehicle sensors and devices, as well as ahuman-machine interface 40, as discussed further below.

As also illustrated in FIG. 2, the vehicle brake control system 70 mayalso communicate with the controller 26 to provide the hitch assistsystem 10 with braking information, such as vehicle wheel speed, and toreceive braking commands from the controller 26. For instance, vehiclespeed information can be determined from individual wheel speeds asmonitored by the brake control system 70. Vehicle speed may also bedetermined from the powertrain control system 72, the speed sensor 56,and the positioning system 22, among other conceivable means. In someembodiments, individual wheel speeds can also be used to determine avehicle yaw rate γ&, which can be provided to the hitch assist system 10in the alternative or in addition to the vehicle yaw rate sensor 58. Thehitch assist system 10 can, further, provide vehicle braking informationto the brake control system 70 for allowing the hitch assist system 10to control braking of the vehicle 12 during backing of the trailer 16.For example, the hitch assist system 10, in some embodiments, mayregulate speed of the vehicle 12 during alignment of the vehicle 12 withthe coupler 14 of trailer 16, which can reduce the potential for acollision with trailer 16, and can bring vehicle 12 to a complete stopat a determined endpoint 35 of path 32. It is disclosed herein that thehitch assist system 10 can additionally or alternatively issue an alertsignal corresponding to a notification of an actual, impending, and/oranticipated collision with a portion of trailer 16. The powertraincontrol system 72, as shown in the embodiment illustrated in FIG. 2, mayalso interact with the hitch assist system 10 for regulating speed andacceleration of the vehicle 12 during partial or autonomous alignmentwith trailer 16. As mentioned above, regulation of the speed of thevehicle 12 may be advantageous to prevent collision with trailer 16.

Additionally, the hitch assist system 10 may communicate withhuman-machine interface (“HMI”) 40 for the vehicle 12. The HMI 40 mayinclude a vehicle display 44, such as a center-stack mounted navigationor entertainment display (FIG. 1). HMI 40 further includes an inputdevice, which can be implemented by configuring display 44 as a portionof a touchscreen 42 with circuitry 46 to receive an input correspondingwith a location over display 44. Other forms of input, including one ormore joysticks, digital input pads, or the like can be used in place orin addition to touchscreen 42. Further, the hitch assist system 10 maycommunicate via wireless communication with another embodiment of theHMI 40, such as with one or more handheld or portable devices 96 (FIG.1), including one or more smartphones. The portable device 96 may alsoinclude the display 44 for displaying one or more images and otherinformation to a user. For instance, the portable device 96 may displayone or more images of the trailer 16 on the display 44 and may befurther able to receive remote user inputs via touchscreen circuitry 46.In addition, the portable device 96 may provide feedback information,such as visual, audible, and tactile alerts.

Still referring to the embodiment shown in FIG. 2, the controller 26 isconfigured with a microprocessor 60 to process logic and routines storedin memory 62 that receive information from the above-described sensorsand vehicle systems, including the imaging system 18, the power assiststeering system 20, the vehicle brake control system 70, the powertraincontrol system 72, and other vehicle sensors and devices. The controller26 may generate vehicle steering information and commands as a functionof all or a portion of the information received. Thereafter, the vehiclesteering information and commands may be provided to the power assiststeering system 20 for affecting steering of the vehicle 12 to achieve acommanded path 32 (FIG. 3) of travel for alignment with the coupler 14of trailer 16. The controller 26 may include the microprocessor 60and/or other analog and/or digital circuitry for processing one or moreroutines. Also, the controller 26 may include the memory 62 for storingone or more routines, including an image processing 64 routine and/orhitch detection routine, a path derivation routine 66, and an operatingroutine 68. It should be appreciated that the controller 26 may be astand-alone dedicated controller or may be a shared controllerintegrated with other control functions, such as integrated with avehicle sensor system, the power assist steering system 20, and otherconceivable onboard or off-board vehicle control systems. It shouldfurther be appreciated that the image processing routine 64 may becarried out by a dedicated processor, for example, within a stand-aloneimaging system for vehicle 12 that can output the results of its imageprocessing to other components and systems of vehicle 12, includingmicroprocessor 60. Further, any system, computer, processor, or the likethat completes image processing functionality, such as that describedherein, may be referred to herein as an “image processor” regardless ofother functionality it may also implement (including simultaneously withexecuting image processing routine 64).

System 10 can also incorporate an imaging system 18 that includes one ormore exterior cameras, which in the illustrated examples include rearcamera 48, center high-mount stop light (CMHSL) camera 50, and side-viewcameras 52 a and 52 b, although other arrangements including additionalor alternative cameras are possible. In one example, imaging system 18can include rear camera 48 alone or can be configured such that system10 utilizes only rear camera 48 in a vehicle with multiple exteriorcameras. In another example, the various cameras 48, 50, 52 a, 52 bincluded in imaging system 18 can be positioned to generally overlap intheir respective fields of view, which may correspond with rear camera48, center high-mount stop light (CMHSL) camera 50, and side-viewcameras 52 a and 52 b, respectively. In this manner, image data 55 fromtwo or more of the cameras can be combined in image processing routine64, or in another dedicated image processor within imaging system 18,into a single image. In an extension of such an example, the image data55 can be used to derive stereoscopic image data that can be used toreconstruct a three-dimensional scene of the area or areas withinoverlapped areas of the various fields of view 49, 51, 53 a, 53 b,including any objects (obstacles or coupler 14, for example) therein. Inan embodiment, the use of two images including the same object can beused to determine a location of the object relative to the two imagesources, given a known spatial relationship between the image sources.In this respect, the image processing routine 64 can use knownprogramming and/or functionality to identify an object within image data55 from the various cameras 48, 50, 52 a, and 52 b within imaging system18. In either example, the image processing routine 64 can includeinformation related to the positioning of any cameras 48, 50, 52 a, and52 b present on vehicle 12 or utilized by system 10, including relativeto the center 36 (FIG. 1) of vehicle 12, for example such that thepositions of cameras 48, 50, 52 a, and 52 b relative to center 36 and/orto each other can be used for object positioning calculations and toresult in object position data relative to the center 36 of vehicle 12,for example, or other features of vehicle 12, such as hitch ball 34(FIG. 1), with known positions relative to center 36.

The image processing routine 64 can be specifically programmed orotherwise configured to locate coupler 14 within image data 55. In theexample of FIGS. 3 and 4, the image processing routine 64 can firstattempt to identify any trailers 16 within the image data 55, which canbe done based on stored or otherwise known visual characteristics oftrailer 16, of an number of different types, sizes or configurations oftrailers compatible with system 10, or trailers in general. When atrailer 16 is identified, system 10 may cause an indication of suchidentification to be presented to the user via the vehicle HMI,including the box 17 shown in FIG. 4, which can be superimposed on theimage presented on HMI 40 by or based on an output from controller 26.In connection with such an identification and indication 17 of trailer16, controller 26 can seek confirmation from the user that theidentification of the trailer 16 is accurate and is the correct trailerfor which to complete an automated hitching operation, as describedfurther below. In the illustrated example, a graphical button 90 can bepresented on HMI 40 adjacent the trailer indication box 17 and the usercan be requested to confirm the trailer identification before controller26 proceeds with the automated hitching operation.

After the trailer 16 is identified, controller 26 may then identify thecoupler 14 of that trailer 16 within the image data 55 based, similarly,on stored or otherwise known visual characteristics of coupler 14 orcouplers in general. In another embodiment, a marker in the form of asticker or the like may be affixed with trailer 16 in a specifiedposition relative to coupler 14 in a manner similar to that which isdescribed in commonly-assigned U.S. Pat. No. 9,102,271, the entiredisclosure of which is incorporated by reference herein. In such anembodiment, image processing routine 64 may be programmed withidentifying characteristics of the marker for location in image data 55,as well as the positioning of coupler 14 relative to such a marker sothat the location 28 of coupler 14 can be determined based on the markerlocation. Additionally or alternatively, controller 26 may seekconfirmation of the determined coupler 14, via a prompt on touchscreen42 similar to the box 17 used to prompt for confirmation the trailer 16.If the coupler 14 determination is not confirmed, further imageprocessing may be provided, or user-adjustment of the position 28 ofcoupler 14 may be facilitated, either using touchscreen 42 or anotherinput to allow the user to move the depicted position 28 of coupler 14on touchscreen 42, which controller 26 uses to adjust the determinationof position 28 of coupler 14 with respect to vehicle 12 based on theabove-described use of image data 55. In various examples, controller 26may initially rely on the identification of trailer 16 for the initialstages of an automated hitching operation, with the path 32 beingderived to move the hitch ball 34 toward a centrally-aligned positionwith respect to trailer 16 with the path 32 being refined once thecoupler 14 is identified. Such an operational scheme can be implementedwhen it is determined that trailer 16 is at a far enough distance fromvehicle 12 to begin backing without knowing the precise endpoint 35 ofpath 32 and can be useful when trailer 16 is at a distance where theresolution of the image data 55 makes it possible to accurately identifytrailer 16, but at which the coupler 14 cannot be precisely identified.In this manner, initial rearward movement of vehicle 12 can allow forcalibration of various system 12 inputs or measurements that can improvethe accuracy of distance measurements, for example, that can help makecoupler 14 identification more accurate. Similarly, movement of vehicle12 resulting in a change to the particular image within the data 55 thatcan improve the resolution or move the coupler 14 relative to theremaining portions of trailer 16 such that it can be more easilyidentified.

In this manner, the initial determination of the position 28 of trailer16 to an accepted level of accuracy is needed for execution of the pathderivation routine 66 and subsequent automated backing of vehicle 12along the path 32. Various characteristics or limitations of system 10may impact the ability of system 10 to identify the trailer 16 (as wellas the coupler 14, whenever such identification is carried out) in thedata 55 received from imaging system 18 under certain conditions or incertain settings. Still further, various vehicle 12 or other system 10characteristics may impact the ability of system 10 to navigate to reacha trailer 16 that is, nevertheless, present within the image data 55.Depending on the particular configuration of system 10, suchcharacteristics can be partially driven by the imaging system 18 used bysystem 10. The imaging system 18 may be limited in its ability toidentify a trailer 16 and/or coupler 14 within the entire field of theimage data 55. In an example, it may be assumed, at least for simplicityof illustration, that system 10 only uses rear camera 48 for trailer 16and coupler 14 detection, with rear camera 48 having a field of view 49that is included in its entirety in the “total field” of the image data55 (notably, if additional cameras 50, 52 a, 52 b are used, the totalfield of the image data 55 would include the entire assembled image fromall such utilized cameras). The imaging system 18 limitations may limitsystem 10 functionality to only a limited distance between trailercoupler 14 and the vehicle 12, as different factors may limit theability of controller 26 in identifying a trailer 16 or its coupler 14when the trailer 16 and vehicle 12 are too close together or too farapart. For example, the resolution of the various cameras 48, 50, 52 a,52 b in imaging system 18 may impact the ability to identify anytrailers 16 or couplers 14 beyond a maximum distance R1 from vehicle 12with the particular value of R1 being influenced by ambient conditions,including available light and/or weather conditions (e.g., rain orsnow).

Additionally, a minimum distance R2 for trailer 16 or coupler 14detection may be realized because certain implementations of system 10may rely on dynamic readings (such as of the ground surface behindvehicle 12 or other features visible around coupler 14) to calibratesystem 10 and or to track vehicle 12 speed in reversing and to track theposition of coupler 14 during system 10 operation. In particular, in theabove example where only rear camera 48 is used by system 10, it may benecessary to detect motion within the field of view 49 to identifydistance to the coupler 14 and to provide accurate tracking and boundaryresolution (an aspect of image processing routine 64). Further, theoperating routine 68 may include a longitudinal control algorithm thatrelies on precise control of the vehicle 12, and a minimum amount oftravel distance corresponding with R2 in an example, is required tocalibrate certain braking and powertrain variables to achieve suchvehicle control. Still further, if a trailer 16 is too close to vehicle12, various features of the trailer 16 may appear as trailers themselvesto the image processing routine 64, meaning that to assist system 10,the trailer 16 should be beyond the minimum distance R2 such that aproportionality of features, including of trailer 16 itself as well asof trailer 16 relative to the total field of image data 55, is optimizedfor image processing routine 64 functionality.

Additionally, other limitations of system 10 functionality may addconstraints to the acceptable zone of operation. In this respect, system10 may not be capable of maneuvering vehicle 12 towards all locations inan initial view of the rear camera 48 (i.e., during trailer 16 orcoupler 14 identification). In particular, system 10 is restricted inits ability to reach a potential target position due, but not limited,to a lateral span that is a function of a distance range and thesteering angle δ limitations of vehicle 12. In one aspect, the maximumsteering angle δ_(max) of the vehicle 12 determines the lateral range,as a function of distance D_(c) to coupler 14, as discussed furtherbelow. In general, an implementation of system 10 may restrictmaneuvering of vehicle 12 to a single reversing motion that, whilepotentially including steering in both the left and right directions,does not incorporate forward driving of vehicle 12 between successiveinstances of reverse driving, for example. In this manner, the maximumlateral distance that can be traversed by vehicle 12 in an automatedhitching operation is limited by the maximum steering angle δ_(max). Asthe vehicle 12 travels laterally by turning the steered wheels 76 andreversing, the lateral limits of system operability 10 are determinedas, essentially, a theoretical hitch ball 34 path extending rearward ofthe vehicle corresponding with steering of vehicle 12 at the maximumsteering angle under reversing of vehicle to either side. In thismanner, the lateral limits of system 10 may extend outwardly fromvehicle 12, with increasing distance away from vehicle 12. In a furtheraspect, the steering angle δ may be limited to an angle δ_(a) that islower than maximum steering angle δ_(max) based on predeterminedconstraints for allowable swing of the front end of vehicle 12. In thismanner, the lateral limits of system 10 functionality may be furtherlimited.

Because of these limitations, the present system 10 may be configured toonly function with trailers 16 and associated couplers 14 positionedinside a “valid” region of space relative to the vehicle 12. The regionis determined by the factors listed above, and, potentially, anyadditional factors that affect the system 10 capability. To ensure suchpositioning of vehicle 12 relative to trailer 16, system 10 can begenerally configured to direct the user to position vehicle 12 relativeto trailer 16 such that trailer 16 is within such a valid area of thefield of view of the utilized cameras, such as field of view 49 of rearcamera 48, and the corresponding image data 55. As shown in FIGS. 3 and4, this direction may be given by way of presenting a target 45 as agraphical overlay on a real-time video image 53 of the image data 55from one or more of the cameras 48, 50, 52 a, 52 b in imaging system 18presented on screen 44. The target 45 may be derived and/or presented onscreen 44 according to various characteristics of system 10 describedabove and may balance these characteristics and system requirements toprovide widely useable functionality of system 10, overall. In thismanner, the target 45 be positioned within the image 53 in a locationthat is determined to correspond with an actual location relative tovehicle 12 relative to the ground plane 30 on which vehicle 12 ispositioned (and on which trailer 16 may be assumed to be present,regardless of actual ground characteristics) that is within the validzone for trailer 16 and coupler 14 detection and vehicle 12 navigationfor alignment therewith. In the example show, the target 45 may notdirectly correspond with the complete area within which such detectionand navigation is possible, but may rather be a general area that isreliably within the acceptable zone, and requires placement of thecoupler 14 and/or trailer 16 within a certain distance from vehicle 12,including within a maximum and minimum distance from vehicle 12, as wellas within a predetermined maximum lateral offset from vehicle 12. Asshown, this may result in the target 45 being positioned generallycentrally within the image 53 in both the horizontal and verticaldirections and may represent, for example about 5-15% of the total areaof image 53. In some instances, target 45 may not be exactly centeredwithin image 53, at least in the vertical direction, with target 45potentially being centered between about 30% and 50% of the verticaldistance of image 54. In various examples, the positioning of theparticular camera(s), such as camera 48, on vehicle 12, as well as thecharacteristics (focal length, etc.) of the camera(s).

When initiated, system 10 can automatically attempt to identify atrailer 16 within the area of target 45 while prompting the driver toposition vehicle 12 such that the coupler 14 and/or trailer 16 is withinthe area of target 45. When a trailer 16, including its coupler 14, aredetected (which would generally coincide with positioning thereof withinthe area of target 45, system 10 can indicate such an identification, asdiscussed above, by highlighting the trailer with box 17 (FIG. 4), whileinstructing the driver to confirm (by pressing button 90, for example)to confirm that the desired trailer 16 has been identified or to selectthe target trailer 16 from one or more identified trailers 16. At whichpoint, vehicle 12, according to various potential interactive schemes,can acquire control of vehicle 12 from the user and can control vehicle12 in aligning hitch ball 34 with coupler 14 for hitching of vehicle 12with the trailer 16.

As shown in FIG. 5, the image processing routine 64 and operatingroutine 68 may be used in conjunction with each other to determine thepath 32 along which hitch assist system 10 can guide vehicle 12 to alignhitch ball 34 and coupler 14 of trailer 16. Upon initiation of hitchassist system 10, such as by user input on touchscreen 42, for example,image processing routine 64 can identify coupler 14 within the imagedata 55 and at least attempt to estimate the position 28 of coupler 14relative to hitch ball 34 using the image data 55 in accordance with oneof the examples discussed above to determine a distance D_(c) to coupler14 and an angle α_(c) of offset between coupler 14 and the longitudinalaxis of vehicle 12. Image processing routine 64 can also be configuredto identify the trailer 16 overall and can use the image data of trailer16, alone or in combination with the image data of coupler 14, todetermine the orientation or heading 33 of trailer 16. In this mannerthe path 32 can further be derived to align vehicle 12 with respect totrailer 16 with the longitudinal axis 13 of vehicle 12 within apredetermined angular range of the heading 33 of trailer 16. Notably,such alignment may not require that the longitudinal axis 13 of vehicle12 is parallel or collinear with the heading 33 of trailer 16, but maysimply be within a range that generally allows connection of hitch ball34 with coupler 14 without collision between vehicle 12 and trailer 16and may, further allow immediate controlled backing of trailer 16 usingvehicle 12. In this manner, the angular range may be such that thealignment of vehicle 12 with trailer 16 at the end of the operatingroutine 68 is such that the angle between longitudinal axis 13 andheading 33 is less than the jackknife angle between the vehicle 12 andtrailer 16 when coupled or a reasonable estimate thereof. In oneexample, the angular range may be such that longitudinal axis 13 iswithin about 30° from collinear with heading 33 in either direction. Invarious examples, such as when the length L of trailer 16 is known, theangular range may be greater, when permitted, or may be less, dependingon the desired tolerance of system 10.

When collected, the position information can then be used in light ofthe position 28 of coupler 14 within the field of view of the image data55 to determine or estimate the height H_(c) of coupler 14. Once thepositioning D_(c), α_(c) of coupler 14 has been determined and,optionally, confirmed by the user, controller 26 can take control of atleast the vehicle steering system 20 to control the movement of vehicle12 along the desired path 32 to align the vehicle hitch ball 34 withcoupler 14, as discussed further below.

Continuing with reference to FIG. 5 with additional reference to FIG. 2,controller 26, having estimated the positioning D_(c), α_(c) of coupler14, as discussed above, can, in one example, execute path derivationroutine 66 to determine vehicle path 32 to align the vehicle hitch ball34 with coupler 14. In particular, controller 26 can have stored inmemory 62 various characteristics of vehicle 12, including the wheelbaseW, the distance from the rear axle to the hitch ball 34, which isreferred to herein as the drawbar length L, as well as the maximum angleto which the steered wheels 76 can be turned δ_(max). As shown, thewheelbase W and the current steering angle δ can be used to determine acorresponding turning radius ρ for vehicle 12 according to the equation:

$\begin{matrix}{{\rho = \frac{1}{W\mspace{11mu}\tan\mspace{11mu}\delta}},} & (1)\end{matrix}$in which the wheelbase W is fixed and the steering angle δ can becontrolled by controller 26 by communication with steering system 20, asdiscussed above. In this manner, when the maximum steering angle δ_(max)is known, the smallest possible value for the turning radius ρ_(min) isdetermined as:

$\begin{matrix}{\rho_{\min} = {\frac{1}{W\mspace{11mu}\tan\mspace{11mu}\delta_{\max}}.}} & (2)\end{matrix}$

Path derivation routine 66 can be programmed to derive vehicle path 32to align a known location of the vehicle hitch ball 34 with theestimated position 28 of coupler 14 that takes into account thedetermined minimum turning radius ρ_(min) to allow path 32 to use theminimum amount of space and maneuvers. In this manner, path derivationroutine 66 can use the position of vehicle 12, which can be based on thecenter 36 of vehicle 12, a location along the rear axle, the location ofthe dead reckoning device 24, or another known location on thecoordinate system 82, to determine both a lateral distance to thecoupler 14 and a forward or rearward distance to coupler 14 and derive apath 32 that achieves the needed lateral and forward-backward movementof vehicle 12 within the limitations of steering system 20. Thederivation of path 32 further takes into account the positioning ofhitch ball 34, based on length L, relative to the tracked location ofvehicle 12 (which may correspond with the center 36 of mass of vehicle12, the location of a GPS receiver, or another specified, known area) todetermine the needed positioning of vehicle 12 to align hitch ball 34with coupler 14. It is noted that hitch assist system 10 can compensatefor horizontal movement Δx of coupler 14 in a driving direction awayfrom axle 84 by determining the movement of coupler 14 in the verticaldirection Δy that will be needed to receive hitch ball 34 within coupler14. Such functionality is discussed further in co-pending,commonly-assigned U.S. patent application Ser. No. 14/736,391 and Ser.No. 16/038,462, the entire disclosures of which are hereby incorporatedby reference herein.

As discussed above, once the desired path 32, including endpoint 35, hasbeen determined using either of the offset determination schemesdiscussed above, controller 26 is then allowed to at least control thesteering system 20 of vehicle 12 with the powertrain control system 72and the brake control system 70 (whether controlled by the driver or bycontroller 26, as discussed below) controlling the velocity (forward orrearward) of vehicle 12. In this manner, controller 26 can receive dataregarding the position of vehicle 12 during movement thereof frompositioning system 22 while controlling steering system 20, as needed tomaintain vehicle 12 along path 32. In particular, the path 32, havingbeen determined based on the vehicle 12 and the geometry of steeringsystem 20, can adjust the steering angle δ, as dictated by path 32,depending on the position of vehicle 12 therealong. It is additionallynoted that in an embodiment, the path 32 may comprise a progression ofsteering angle δ adjustment that is dependent on the tracked vehicleposition.

As illustrated in FIG. 5, vehicle path 32 can be determined to achievethe needed lateral and rearward movement within the smallest areapossible and/or with the lowest number of maneuvers. In the illustratedexample of FIG. 5, path 32 can include two portions defined by steeringof wheels 76 in different directions to collectively traverse the neededlateral movement of vehicle 12, while providing final straight, rearwardbacking segment to bring hitch ball 34 into the above-described offsetalignment with coupler 14. It is noted that variations in the depictedpath 32 may be used. It is further noted that the estimates for thepositioning D_(c), α_(c) of coupler 14 may become more accurate asvehicle 12 traverses path 32, including to position vehicle 12 in frontof trailer 16 and as vehicle 12 approaches coupler 14. Accordingly, suchestimates can be continuously derived and used to update path derivationroutine 66, if necessary, in the determination of the adjusted endpoint35 for path 32, as discussed above. In a similar manner, the path 32, asderived using the position and orientation data acquired from smartphone96, can be fine-tuned once the image processing routine 64 can identifycoupler 14 in the image data 55, with continued updates for path 32being similarly derived as the image data 55 becomes increasingly clearduring the approach toward trailer 16. It is further noted that, untilsuch a determination can be made, the dead reckoning device 24 can beused to track the location of vehicle 12 in its movement along path 32toward the initially-derived endpoint 35.

As discussed above, system 10 requires the availability of a number ofmeasurements obtained using imaging system 18 and, optionally, varioussensors 54 and devices 22, as well as reliable control of the steering,20, powertrain 72 and braking 70 systems to implement the imageprocessing 64, path derivation 66, and operating routines 68 for controlthe backing of vehicle 12 according to the process described above.Accordingly, the inability of system 10 to obtain any such measurementsor to reliably control any of the involved vehicle systems can impactthe ability of system 10 to reliably carry out the above hitchingprocess. Accordingly, system 10 may also be configured to providemultiple levels of hitching assistance depending on both userpreference, as well as measurement availability and control reliability.For example, a user may not feel comfortable relinquishing control(completely or at all) of vehicle 12, but may still prefer some level ofguidance in aligning hitch ball 26 with coupler 14. In other examples,visibility by way of available light or weather may impact the abilityof system 10 locate or track coupler 14, even when trailer 16 is withinthe above-described acceptable zone, or system 10 may determine that forvarious reasons, the steering 20 and braking 70 systems cannot bereliably controlled. Generally, control of the steering 20 system may beimpacted by vehicle 12 being positioned on a transverse slope, which maycause wheel slip to cause vehicle 12 to travel on an unexpected path,and moisture, for example, may cause the brake system 70 functionality.Still further, positioning of vehicle 12 on soft ground or on an upwardor downward slope may make powertrain 72 or braking 70 system controloperate out of an optimal range. These or other conditions may diminishto the point where reliable control by system 10 is not available.

To address any of the above, or other similar potential, scenarios,system 10 may include additional functionality according to FIGS. 6-8.In one example, system 10 may be configured to additionally operate in a“basic” mode, where various vehicle paths are displayed on screen 42 asan overlay on the image data 55. As shown, the paths may include avehicle path 92 that extends rearward of approximations of the rearcorners of vehicle 12 and adjusts dynamically based on the steeringangle δ detected by steering angle sensor 78. The paths may furtherinclude a hitch ball path 94 that extends generally from the center ofthe rear of vehicle 12 so as to align with the hitch ball 34 of vehicle12 and to show a projected path of the hitch ball 34, given the detectedsteering angle δ. In addition, system 10 may also overlay a brakingindication image 96 that can signal to the user when system 10determines, such as by use of proximity sensors 54, that the coupler 14is in a position relative to vehicle 12 to be at least longitudinallyaligned with hitch ball 34. These paths 92, 94 are based on calculationsregarding the steering angle δ and, therefore, are not susceptible tothe visibility requirements discussed above for the various operatingroutines 64, 66, 68. Similarly, the proximity sensors 54 may beultrasonic or the like and, accordingly, do not require any ambientlight to function and may be less susceptible diminished functionalitydue to weather conditions. Further, the presentation of such paths 92,94, and the braking image 98 on image 53 allows for continuingassessment and adjustment by the driver should wheel slip or diminishedbraking functionality result in hitch ball 34 not following path 94,exactly. Accordingly, such a “basic” mode may be available under allconditions, subject to an assessment by the user that the coupler 14 isvisible to the user on display 42.

In an additional level of functionality, when coupler 14 can beidentified by system 10, but steering system 20, braking system 70 andpowertrain system 72 cannot be controlled with acceptable reliability,system may offer an “ideal” path 100 based on the user of the imageprocessing 64 and path derivation 66 routines that can represent a path32 determined by system 10 to align hitch ball 34 with coupler 14. Whenpresent, the user can adjust the steering input for vehicle 12 such thatthe hitch ball path 94 aligns with the ideal path 98 during reversing,while also controlling steering and braking until system 10 presents thebraking indication 96 or the driver determines that appropriatelongitudinal positioning has been achieved. Still further, system 10 mayprovide automatic steering of vehicle 12 by control of steering system20 to maintain vehicle 12 along the determined path 32 while the usercontrols the operation of powertrain 72 and braking 70 system to controlthe speed of vehicle 12. This functionality can be used, for example,where visibility or ground conditions, for example allow for coupler 14detection, but not ground tracking, or where powertrain 72 and/or brakesystem 70 cannot be controlled with the required accuracy, as discussedabove. Finally, when the above-described conditions are met, theoperability described above, including full control of vehicle 12 can beachieved.

System 10, when providing the various levels of functionality discussedabove, can additionally operate according to the scheme 200 depicted inthe flow chart of FIG. 7, wherein, upon activation 202 of system 10, thevarious hitch assist modes are presented 204 on the HMI 40 as selectableoptions respectively corresponding with the “basic” 102, “guided path”104, automated steering 106, and full-control 108 modes discussed above.In one example, when presenting 202 such options, system 10 can firstassess 204 availability of the various control modes, according to anassessment of the various characteristics discussed above, and can onlypresent available options, or can display all options, with anyunavailable options being indicated as un-selectable (such as by beingdimmed, crossed out, greyed out, or the like). The system 10 can thenreceive 206 a mode selection from the user, which may be stored as adefault mode or may be single-instance selection, before activating 208the selected functionality according to the selected mode, which mayremain the mode for subsequent operations until changed 210 by the user.

Turning to FIGS. 9-17B various additional examples of executing theabove-described full control hitch assist functionality by guiding theuser to an initial vehicle 12 alignment with the subject trailer 16 inan initial acceptable zone are described. In one example, shownparticularly in FIGS. 9-13, the target 45 may be displayed in a shapethat more directly corresponds with the actual acceptable zone fortrailer 16 and coupler 14 positioning relative to vehicle 12, which mayprovide increased flexibility and greater understanding of the system 10requirements for the user compared to the generalized target of FIGS. 3and 4. As discussed above, the visibility requirements of the operatingroutines 64,66,68 may dictate that trailer 16 (or at least coupler 14)be positioned between a longitudinal range between limits R1 and R2 thatcorrespond with distance from the vehicle 12, as shown in FIG. 9. Asalso shown in FIG. 9, the lateral range for the acceptable zone extendsbetween the lateral limits L1 and L2, which as discussed above extendoutwardly from the hitch ball 34 along “maximum steerable” pathscorresponding with a maximum or maximum allowed steering angle δ_(max)or δ_(a) in both the left and right directions. In this manner, theacceptable zone 110 is an area along the ground plane 30 that is withinboth the longitudinal range and the lateral range and is, therefore, anarea bounded by respective portions of the longitudinal limits R1,R2 andthe lateral limits L1,L2.

As shown in FIG. 10, in an example, the target 45 can be presented onscreen 42 as an overlay on the video image 53 displayed using the imagedata 55 that approximates the acceptable zone 110 on the image 53. Inthis manner, the respective portions of the ranges R1, R2, L1, L2bounding the acceptable zone 110 can be graphically represented onscreen 42 in a manner that correlates the acceptable zone 110 on theactual ground plane 30 with the view on the screen 42 based on theproperties of camera 48, for example, and the position thereof to arriveat a perspective projection of the acceptable zone that at leastreasonably appears as an area of the ground visible on the screen 42. Inthis manner, the user may position vehicle 12 such that the subjecttrailer is within the target 45 corresponding with the acceptable zone110. In the example illustrated in FIG. 11, once such positioning isachieved and system 10 detects at least trailer 16 within the acceptablezone 110 or aligned with target 45, the indication 17 of trailer 16identification can be overlaid on trailer 16 within image 53 and button90 can be displayed for user confirmation of the intended trailer 16. Inan alternative confirmation scheme, depicted in FIG. 12, system 10 canseek confirmation based on user action other than a touch on HMI 40. Asshown, system 10 can present a prompt 108 on display 42 for the user tostop the vehicle 12 to initiate the hitching operation.

As shown in FIGS. 13-17B positioning of vehicle 12 with trailer 16positioned in the acceptable zone 110 can be “coached” by system 10depicting the target 45 as, essentially, a void area within a depictedinvalid zone 112 overlaid on image 53, as shown in FIG. 13. It is notedthat the invalid zone 112 can simply be an inverse of the target 45depicting the acceptable or “valid” zone 110, shown in FIGS. 10 and 12.For illustration purposes, the invalid zone 112 is depicted differentlyto illustrate the effect of varying system 10 constraints that canresult in a larger valid zone 110, as shown in FIG. 14. In one aspect,system 10 can utilize the invalid zone 112 in a similar manner to thevalid zone 110 target 45 discussed above with respect to FIGS. 9-12. Inanother example, system 10 can operate according to the scheme 300depicted in FIG. 14, in which upon activation 302, system 10 causes theinvalid zone 112 image to be presented 304 on display 42 as an overlayon the image 53 of the data 55 from camera 48, for example. The system10 then relies on the user to assess 306 whether the trailer 16 is in avalid position (i.e. outside of the invalid zone 112) and to correct 308the vehicle position, if needed. When the positioning is correct, theuser can indicate 310 the trailer position by a touch input on screen42, which the system 10 can use to narrow the field for image processingroutine 64, which can then be used to identify 312 trailer 16 (andcoupler 14 in an example) before ending the selection routine 314.

In another example, system 10 can operate by the scheme 400 of FIG. 16,wherein, upon activation 402, system 10 waits for a user indication 402of the trailer 16 position via a touch input on screen 42 (as shown inFIG. 17A). If possible, the system 10 can identify 406 the trailer 16using image processing routine 64 in connection with the touch input. Ifthe trailer 16 is identified, system 10 can analyze 408 the trailer 16position and can determine 410 whether trailer 16 is in the valid zone110. If the trailer 16 is not in the valid zone 110 (or cannot beidentified, indicating, potentially, that the trailer is outside of thelongitudinal range), system 10 can then present 412 the invalid zone andinstruct 414 the driver to reposition 416 the vehicle 12 accordingly,while maintaining 418 the tracking of the trailer 16 (if detected) untiltrailer 16 is in the valid zone 110. When trailer 16 is identifiedwithin the target zone 110, system 10 can end the identification schemeand can proceed to the available guidance operation, as discussed above.

As shown in FIG. 18, system 10 may utilize the various exterior lightson and/or directed away from the rear of vehicle 12 to illuminate thearea behind vehicle 12 to improve the ability of system 10 to locate andtrack trailer 16 and coupler 14 during the operation of at least theimage processing routine 64 and operating routine 68. As illustrated,such lights may include the right 114 a and left 114 b brake lights, thecenter high-mount stop light (“CMHSL”) 116, and the tailgate light 118,and may vary in the particular arrangement and lights included,depending on the vehicle 12 configuration. In this manner, more or fewerlights may be present with vehicle 12, for example, potentially furtherincluding backup lights, taillights, etc. In the illustrated example,system 10, upon activation can illuminate the depicted right 114 a andleft 114 b brake lights, CMHSL 116, and the tailgate light 118,regardless of detected conditions or may analyze the image data 55 todetermine the lighting conditions or to make an initial assessmentregarding potential impact of weather conditions on the ability toidentify one or more trailers 16 within the field of view 49 of camera48, for example. Such illumination can be initiated by system 10 by wayof communication with the vehicle lighting control system orfunctionality. As shown in FIG. 19, in one implementation, system 10 mayoperate 500 by a process including initially detecting the ambientlighting level, either using the camera 48 (for example) or using othervehicle sensors (steps 502 a or 502 b). System 10 can then determine 504whether the available lighting is sufficient and proceed 506 with theautomated hitching operation (as discussed above) or may activate508,510 the available exterior lighting before performing 512 thehitching operation with the additional lighting and deactivating 514a,514 b the exterior lighting (or allowing it to return to an initialstate) when the operation is complete.

The additional illumination provided by the illustrated lights 114 a,114 b, 116, 118 may facilitate the identification by system 10 of anytrailers 16 within the field of view 49 of camera 48, for example, byimproving the contrast and/or resolution of the image data 55 availableto system 10, particularly in the area where the illumination of suchlights overlaps. As shown in FIG. 18, in some vehicle 12 and lightingconfigurations, the area where the illumination areas 120 a, 120 b, 122,124 (of lights 114 a, 114 b, 116, 118, respectively) overlap may whollyor partially coincide with all or part of the acceptable zone 110,thereby providing the ability of system 10 to reliably utilize thetarget 45 discussed above for vehicle 12 and trailer 16 alignment in anincrease range of ambient conditions, including those with low ambientlight, and the like. In this manner, the acceptable zone 110 andresulting target configuration 45 may dynamically adjust in size orconfiguration (particularly with respect to the longitudinal rangelimits R1, R2) depending on the available light and/or the use of theexterior lighting during image processing routine 64. In anotherexample, target 45 can be sized and configured based on limits R1, R2during low-light conditions augmented by exterior light illumination tomore reliably ensure system 10 reliability without requiring priorcondition detection.

Turning now to FIGS. 20-23, once the trailer 16 and coupler 14 have beenidentified, and system 10 determines the path 32 to align hitch ball 34with the coupler 14, the operating routine 68 may continue to guidevehicle 12 until hitch ball 34 is in the desired position 38 _(d)relative to coupler 14 for coupler 14 to engage with hitch ball 34 whencoupler 14 is lowered into horizontal alignment therewith. In theexample discussed above, image processing routine 64 continuouslymonitors the positioning D_(c), α_(c) of coupler 14, constantly or onceavailable, during execution of operating routine 68, including ascoupler 14 comes into clearer view of rear camera 48, as shown in FIG.21, with continued movement of vehicle 12 along path 32, as shown inFIG. 20. As discussed above, the position of vehicle 12 can also bemonitored by dead reckoning device 24 with the position 28 of coupler 14being continuously updated and fed into path derivation routine 66 incase path 32 and or endpoint 35 can be refined or should be updated (dueto, for example, improved height H_(c), distance D_(c), or offset angleα_(c) information due to closer resolution or additional image data 55),including as vehicle moves closer to trailer 16, as shown in FIG. 22.Still further, the coupler 14 can be assumed to be static such that theposition of vehicle 12 can be tracked by continuing to track the coupler14 to remove the need for use of the dead reckoning device 24. In asimilar manner, a modified variation of operating routine 68 canprogress through a predetermined sequence of maneuvers involvingsteering of vehicle 12 at or below a maximum steering angle δ_(max),while tracking the position D_(c), α_(c) of coupler 14 to converge theknown relative position of hitch ball 34 to the desired position 38 dthereof relative to the tracked position 28 of coupler 14, as discussedabove and shown in FIG. 23.

Turning now to FIG. 24, a flowchart showing steps in one operatingscheme 600 for using hitch assist system 10 to align a vehicle hitchball 34 with a trailer coupler 14 is shown. In particular, in step 602,the hitch assist system 10 is initiated. Once the hitch assist system 10is initiated 602, controller 26 can use imaging system 18 to scan theviewable scene using any or all available cameras 48, 50, 52 a, 52 b(step 604). The scene scan (step 612) can be used to then identify 606the trailer 16 and coupler 14, which may be confirmed by the user, whichmay proceed using target 45 on vehicle HMI 40, as discussed in any ofthe schemes discussed above.

If the coupler 14 can be identified (step 608) in the image data 55, theheight H_(c) distance D_(c), and offset angle α_(c) of coupler 14, asidentified in step 606, can then be determined using the available imagedata 55 (step 606) as discussed above, including using image processingroutine 64. As discussed above, image processing routine 64 can beprogrammed or otherwise configured to identify coupler 14 of trailer 16within image data 55 (step 606). In this manner, after the results ofthe initial scene scan (step 604) are analyzed, controller 26 candetermine if coupler 14 has been confirmed by the user (such as by wayof HMI 40). If coupler 14 has not been confirmed or if a determinedcoupler 14 has been rejected, the scene scan (step 604) can becontinued, including while instructing driver to move vehicle 12 tobetter align with trailer 16, including by positioning the trailer 16and/or coupler 14 within any of the above-descried targets 45, untilcoupler 14 is identified.

When coupler 14 has been identified and confirmed, the path derivationroutine 66 can be used to determine the vehicle path 32 to align hitchball 34 with coupler 14 in step 610. In this manner, the positioningD_(h), β_(h) of coupler 14 is extracted from the image data 55 and usedto place the coupler 14 within the stored data relating the imagecoordinates with the real-world coordinates of the area surroundingvehicle 12. In doing so, controller 26 uses path derivation routine 66to determine path 32 to align hitch ball 34 with the predicted position28 of coupler 14 to an engaging position over hitch ball 34, asdescribed above with respect to FIGS. 20-23.

Once the path 32 has been derived, hitch assist system 10 can ask theuser U to relinquish control of at least the steering wheel of vehicle12 (and, optionally, the throttle 73 and brake, in the implementation ofhitch assist system 10 described above wherein controller 26 assumescontrol of powertrain control system 72 and brake control system 70during execution of operating routine 68). When it has been confirmedthat user U is not attempting to control steering system 20 (forexample, using torque sensor 80, as discussed above), controller 26begins to move vehicle 12 along the determined path 32. Hitch assistsystem 10 then controls steering system 20 (step 612) to maintainvehicle 12 along path 32 as either user U or controller 26 controls thevelocity of vehicle 12 using powertrain control system 72 and brakingcontrol system 70. As discussed above, controller 26 or the user cancontrol at least steering system 20, while tracking the position D_(c),α_(c) of coupler 14 until vehicle 12 reaches endpoint 35 (step 614),wherein the vehicle 12 hitch ball 34 reaches the desired position 38_(d) for the desired alignment with coupler 14, at which point operatingroutine 68 can end (step 618), either by controlling brake system 70 tocause vehicle 12 to stop (which can be done progressively as vehicle 12approaches such a point), or by issuing a command to the user to stopvehicle 12 (which can also be done progressively or by a countdown asvehicle 12 approaches the desired location) before deactivating hitchassist system 10. Vehicle 12 can then be driven normally with system 10remains idle until a reactivation input 620 is received, at which pointthe above-described method restarts at the scanning step 604.

It is to be understood that variations and modifications can be made onthe aforementioned structure without departing from the concepts of thepresent invention, and further it is to be understood that such conceptsare intended to be covered by the following claims unless these claimsby their language expressly state otherwise.

What is claimed is:
 1. A vehicle hitching assistance system, comprising:a controller: acquiring image data from the vehicle; executing aninitial alignment process, including: illuminating one or more exteriorlights directed toward a rear of the vehicle prior to acquiring theimage data from the vehicle; searching for a trailer, positioned past aminimum distance from the vehicle, within a specified area of the imagedata, the specified area being less than a total field of the image datain directions corresponding with both a longitudinal distance betweenthe vehicle and the trailer and a lateral direction perpendicular to thelongitudinal distance; and presenting an indication to a driver of thevehicle to reposition the vehicle when the trailer is not identifiedwithin the specified area and removing the indication when the traileris identified within the specified area, the trailer remaining past theminimum distance from the vehicle; and executing an automated backingprocess upon identifying the trailer within the specified area,including identifying a coupler of the trailer and outputting a steeringsignal to the vehicle to cause the vehicle to steer to align a hitchball of the vehicle with the coupler of the trailer during reversing ofthe vehicle toward the trailer.
 2. The system of claim 1, wherein thecontroller acquires the image data from an imaging system included withthe vehicle, the imaging system having at least one camera, the totalfield of the image data corresponding with a total field of view of theat least one camera.
 3. The system of claim 2, wherein: the controlleroutputs the steering signal to a steering system included with thevehicle; and the controller derives the steering signal based on atleast a maximum steering angle of the steering system.
 4. The system ofclaim 1, wherein the specified area of the image data is a circulartarget area disposed within a central portion of the image data.
 5. Thesystem of claim 1, wherein the specified area of the image data iswithin a designated boundary comprising respective portions based on aresolution of the image data, a proportion of the trailer relative tothe total field, and a known steering limit of the vehicle.
 6. Thesystem of claim 5, wherein the respective portions of the designatedboundary are based on a correlation of the total field of the image datawith an area of an assumed ground plane on which the vehicle ispositioned visible within the total field.
 7. The system of claim 6,wherein the area of the assumed ground plane includes: a maximum couplerdetection distance corresponding with the resolution of the image data;a minimum trailer identification distance corresponding with theproportion of the trailer relative to the total field; and left andright maximum steerable paths extending from the vehicle in a reversingdirection corresponding with the known steering limit of the vehicle. 8.The system of claim 1, wherein, during the initial alignment process,the controller further outputs a video image displayable on ahuman-machine interface within the vehicle including: the image data; agraphic overlay of the specified area on the image data in aproportionally correlated manner; and a message indicating to the driverof the vehicle to reposition the vehicle until the trailer is identifiedwithin the specified area.
 9. The system of claim 8, wherein thecontroller begins executing the initial alignment process, includingoutputting the graphic overlay and message in the video image, uponactivation of the system.
 10. The system of claim 9, wherein, during theinitial alignment process, the controller: receives an input from thehuman-machine interface corresponding with a user indication of atrailer within the image data; and outputs the graphic overlay andmessage in the video image only after receiving the user indication ofthe trailer within the image data and failing to identify any trailerwithin the specified area of the image data.
 11. The system of claim 1,wherein the controller: during the initial alignment process, identifiesthe trailer within the specified area of the image data and determinesif a sensing condition and a visibility condition are met; executes theautomated backing process, including identifying the coupler of thetrailer and outputting the steering signal to the vehicle to cause thevehicle to steer to align the hitch ball of the vehicle with the coupleras a part of a first hitch assist mode when the sensing condition andvisibility condition are not met; further implements a second hitchassistance mode when one of the sensing condition and the visibilitycondition are not met, the second hitch assistance mode includingpresenting an image of a best fit path to align the hitch ball with thecoupler to the user for guiding user control of the vehicle in reversingthe vehicle toward the trailer; receives a selection signal from thevehicle corresponding with a user selection of a mode beforeimplementing either the first or second hitch assistance mode; andcauses the vehicle to present an indication that the first hitch assistmode may not be selected when one of the sensing condition and thevisibility condition are not met.
 12. A vehicle, comprising: a steeringsystem; at least one exterior light mounted on and directed away from arear of the vehicle; and a controller: acquiring image data from thevehicle; executing an initial alignment process, including: illuminatingthe at least one exterior lights directed toward a rear of the vehicleprior to acquiring the image data from the vehicle; searching for atrailer, positioned at a distance from the vehicle, within a specifiedarea of the image data, the specified area being less than a total fieldof the image data in directions corresponding with both a longitudinaldistance between the vehicle and the trailer and a lateral directionperpendicular to the longitudinal distance, the specified area furtherbeing located within an area to the rear of the vehicle illuminated bythe at least one exterior light; presenting an indication to a driver ofthe vehicle to reposition the vehicle when the trailer is not identifiedwithin the specified area and removing the indication when the traileris identified within the specified area; and executing an automatedbacking process only upon identifying the trailer within the specifiedarea, including outputting a steering signal to the vehicle steeringsystem to align a hitch ball of the vehicle with a coupler of thetrailer during reversing of the vehicle toward the trailer.
 13. Thevehicle of claim 12, wherein after identifying the trailer within aspecified area of the image data, the controller identifies the couplerof the trailer during execution of the automated backing process. 14.The vehicle of claim 12, wherein the specified area of the image data iswithin a designated boundary comprising respective portions based on aresolution of the image data, a proportion of the trailer relative tothe total field, and a known steering limit of the vehicle.
 15. Thevehicle of claim 14, wherein the respective portions of the designatedboundary are based on a correlation of the total field of the image datawith an area of an assumed ground plane on which the vehicle ispositioned visible within the total field.
 16. The vehicle of claim 14,wherein illumination of the at least one exterior light facilitatesidentifying the trailer within the image data.
 17. The vehicle of claim12, wherein the at least one exterior light includes at least one of aleft brake light, a right brake light, a tailgate light, and a centerhigh-mount stop light mounted on respective portions of an exterior ofthe vehicle.
 18. A method for assisting a vehicle in hitching with atrailer, comprising: acquiring image data for a field of view away froma rear of the vehicle; executing an initial alignment process,including: illuminating one or more exterior lights directed toward arear of the vehicle prior to acquiring the image data from the vehicle;searching for a trailer, past a minimum distance from the vehicle,within a specified area less than the field of view of the image data,the specified area being less than a total field of the image data indirections corresponding with both a longitudinal distance between thevehicle and the trailer and a lateral direction perpendicular to thelongitudinal distance; and presenting an indication to a driver of thevehicle to reposition the vehicle when the trailer is not identifiedwithin the specified area and removing the indication when the traileris identified within the specified area, the trailer remaining past theminimum distance from the vehicle; and executing an automated backingprocess upon identifying the trailer within the specified area,including identifying a coupler of the trailer and outputting a steeringsignal to cause the vehicle to steer to an align a hitch ball of thevehicle with the coupler during reversing of the vehicle toward thetrailer.
 19. The vehicle of claim 12, wherein the controller furtherindicates to a driver of the vehicle to reposition the vehicle until thetrailer is identified within the specified area.